This proposal aims to investigate the process by which cytoplasmic determinants are localized for the establishment of spatial pattern in the developing egg of the fruit fly Drosophila melanogaster. cappuccino (capu) and spire (spir) are maternal effect loci in Drosophila that, when mutant, affect both the dorsal-ventral and anterior-posterior axes of the egg and embryo (Manseau and Schupbach, 1989a). Morphological and genetic evidence indicates that the genes are involved in localizing determinants during oogenesis. They act upstream of all the known members of the posterior group of genes and are required for localizing all identified components of the specialized pole plasm, necessary for formation of the abdomen and pole cells, to the posterior pole of the oocyte. A major goal of this proposal is to more directly address the biochemical function of capu and spir through a molecular analysis of the genes. Both genes will be isolated and the sequence of the coding regions will be determined. The cloned genes will be used as probes to analyze the distribution of encoded mRNA in wild-type ovaries and in ovaries that are mutant for members of the posterior and dorsal-ventral groups of maternal effect genes. If the mRNA is found to be localized within the oocyte, then regions of the mRNA responsible for this localization will be identified. Antibodies Will be made against the proteins and the distribution of the protein products will be examined in wild-type and mutant ovaries. If the protein is distributed throughout the oocyte, then we will determine whether it is associated with the cytoskeleton. The molecular lesions will be identified in the mutant capu and spir alleles. The morphological and genetic characterization of the mutant phenotype of capu and spir will continue. The cytoskeleton will be examined in oocytes of capu and spir mutant females by immunofluorescent confocal microscopy. Loci that are good candidates for encoding molecules that physically interact with capu and spir will be tested for genetic interactions with capu and spir.